This invention relates to fluid power mechanical devices of the type that use reciprocating pistons in sleeves or in rotary cylinder barrels and specifically to an improved means of: (i) communicating the primary working fluid to and from the pistons (ii) varying displacement of the mechanism and (iii) improving some of the critical bearing load conditions.
For the purpose of convenience the invention will be described as a fluid pump, but it should be understood that the term pump when used hereafter embraces both a fluid pump and a fluid motor; also the term fluid embraces both the liquid or gaseous state or some mixture thereof.